System Introspection for System Analysis on Mobile Devices

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Mobile Device LaptopTest No. Delay AVG STDEV AVG STDEVSingleline1 100ms 13.01ms 15.42ms 2.67ms 5.44ms4 500ms 8.7ms 9.79ms 6.05ms 7.18ms7 1000ms 14.52ms 15.54ms 10.15ms 32.17msMultiline2 100ms 13.74ms 11.53ms 5.16ms 10.17ms5 500ms 19.21ms 12.07ms 11.05ms 16.88ms8 1000ms 25.34ms 13.8ms 9.83ms 19.14msComplexData3 100ms 291.15ms 101.34ms 284.99ms 144.74ms6 500ms 281.85ms 41.47ms 265.55ms 92.49ms9 1000ms 323.24ms 50.65ms 261.7ms1 38.9msTable 7.3: Results of the latency evaluation - For each device connectedthe average (AVG) and the standard deviation(STDEV) of the latency is displayed. The results are dividedinto the different delays <strong>for</strong> the pattern attached toa single message (Singleline, Multiline and ComplexData).depends on the network and not on the processing power of the client.7.3 Observing the CPU Load of the Robot <strong>System</strong>To observe a robot and to get an idea of the inner processes, the robot itselfmust offer an interface to query the desired in<strong>for</strong>mation. One idea is to makethe robot publishing its in<strong>for</strong>mation at any time. This way often results inloosing needed resources (e.g. additional bandwidth usage even if data is notconsumed). The system developed in this thesis uses the first way and queriesin<strong>for</strong>mation of the robot only if a developer needs the in<strong>for</strong>mation. But eventhis technique needs to trigger a process on the robot to gather the in<strong>for</strong>mationand <strong>for</strong>ward it. Due to the fact that this process uses system resources itsobvious that the systems per<strong>for</strong>mance is influenced. One requirement was tominimize this influence when using the probe (see chapter 3).7.3.1 GoalThe following evaluation was done to check the system developed in this thesis.Does the implementation consume more resources than available on the robot?Could actively observing the robot result in interruption of the normal behaviorcompared to the behavior without the probe active? To check the influencethe system will be observed with and without the probe active.59
For this thesis only a rough estimate can be given on the collected data due tothe fact that the robots behavior is never constant. The navigation control ofthe robot does not create the same path <strong>for</strong> every run. Also several controllingprocesses run in parallel which results in different executions <strong>for</strong> same startingconditions. For the evaluation the assumption is made, that every test run isnearly the same and the collected data of the different runs can be aligned. Tomake a statement about the results, the average of the runs with and withoutthe probe is analyzed.7.3.2 PreparationsThe different components of the robot are controlled by two laptops placed inthe backpack. The laptop controlling the cameras and the speech recognitionwill be referred to as upper laptop, the laptop controlling the navigation willbe referred to as lower laptop. To measure the system load the ToBI plat<strong>for</strong>mis running a predefined navigation procedure traveling along a defined course(Figure 7.2). Through the course four points must be reached by the robot.One round through the course takes the robot 45 seconds. The starting positionof the robot is marked to the ground and <strong>for</strong> each test the robot is placed onthat position. Monitored are both laptops controlling the robot. Each laptop issynchronized against a NTP daemon running on the third laptop. To measurethe CPU load a special tool is written. This tool reads the current CPU load inpercent and appends the results to a file on the local file system. To minimizethe influence of this tool it only collects the data with a frequency of 250 ms.For each test a total of 180 data points is written to the logging file.7.3.3 MethodFor this evaluation a total of 20 runs is per<strong>for</strong>med. For each test the robotnavigates to four predefined points. The first ten runs the probe is not active.On the next ten runs the probe is activated and one client is connected.Be<strong>for</strong>e every test starts the robot is placed at the starting position and thesystem clocks on the main laptops get synchronized. When a single test isexecuted, the logging tool is started synchronously on both laptops and thenavigation procedure starts. After 45 seconds each logging tool automaticallystops recording and writes the result file to the file system.60
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Bringing System <s
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AbstractSystem <st
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output, so each component is offeri
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of the system and the decisions mad
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created a telelaboratory where two
Page 13 and 14: Like the telelaboratory there is a
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Page 29 and 30: Figure 5.4: Beacon running between
Page 31 and 32: Figure 5.5: Reading and processing
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Page 35 and 36: For example a developer can select
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Page 47 and 48: The selected sensors give a good im
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Page 51 and 52: TabConfig - The Status ViewThe TabC
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Page 55 and 56: LoginController which also observes
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Page 59 and 60: 7 EvaluationIn the previous chapter
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Page 69 and 70: 8 ConclusionsIn the context of this
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Page 74: BibliographyBurrell, A. and A. Soda
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Page 79 and 80: AppendixUse CasesUse Case 1: Connec
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Page 83 and 84: Use Case 9: Sending beacon to keep
Page 85 and 86: Figure 9.4: Latency of receiving da
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